In recent years, charged particle beam devices such as a scanning electron microscope (SEM), a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), a focused ion beam (FIB) processing and observation system have been used to observe minute regions. In these devices, a sample is irradiated with a charged particle beam such as an electron beam and an ion beam. For example, when a sample is irradiated with an electron beam, secondary electrons, reflection electrons, etc., are emitted from the front surface of the sample and transmission electrons are emitted from the rear surface thereof. Herein, an emission amount of these electrons (i.e., charged particles) has angular dependence so that the emission amount thereof changes associated with an emission angle, as depending on a shape and a composition, etc., of the sample. Accordingly, a device which detects those electrons at the most suitable angle has been proposed in case an emission amount of electrons has angular dependence (see Patent Literature 1, etc.).